1. Field of the Invention
The present invention relates to a turbocharger for an internal combustion engine.
2. Description of the Related Art
Sensor elements for detecting at least a portion of at least one gas component of a gas, such as an exhaust gas, in a measuring-gas chamber, especially in an exhaust-gas tract, are known from the related art. For example, such sensor elements are described in Robert Bosch GmbH: Sensors in the Motor Vehicle, 1st edition 2010, pages 160-165. The sensor elements may be used in the automotive field, for example. The measuring gas chamber in particular could be the exhaust-gas tract of a combustion engine, for instance, and the sensor element a lambda probe. The core of the sensor element, especially the lambda probe, usually is a technical ceramic, which may be destroyed if, for instance, large mechanical tensions occur in the sensor element. For example, tensions, especially mechanical tensions, could be produced by local cooling of the, in particular, hot technical ceramic, for example, especially a ceramic, due to impinging water drops, for instance. Sensor elements known from the related art are normally situated within the exhaust-gas tract in the exhaust direction, especially in the flow direction of the exhaust gas, downstream from a turbocharger and preferably upstream from a catalytic converter, especially a three-way catalytic converter. Water loading, especially in conjunction with an increasing likelihood of impinging water drops, is usually greatest during a cold engine start. In an engine operation with a cold exhaust-gas tract, e.g., during the cold engine start, exhaust-gas moisture may condense on walls, the exhaust-gas tract, for example, encompassing at least one cylinder outlet, at least one manifold, at least one turbocharger, especially at least one exhaust turbocharger, and at least one three-way catalytic converter. An exhaust gas mass flow can carry exhaust gas condensate along, especially in such a way that a high moisture load of a downstream lambda probe often comes about as a result.
The related art describes various strategies for protecting the sensor element, especially the functional ceramic, from damage, in particular damage resulting from stresses. For example, the technical ceramics may be heated to operating temperature only after a so-called dew point end instant has been reached. In a cold state, especially prior to the dew point end, the mechanical stresses in the sensor element caused by the admission of water are generally non-critical. One particular disadvantage of this strategy is a late operating readiness of the sensor element, especially a probe, following the engine start.
In another strategy, the sensor element may be enclosed by a water-proof protective coat, for example, which is able to distribute local cooling, preferably across a large surface. One particular disadvantage in this case may be a limited absorption capacity of the protective coat with regard to moisture. Another disadvantage may be an increased heating power requirement, especially if large exhaust gas mass flows are involved.
The classic installation position of the sensor element, especially the lambda probe, known from the related art, such as between the turbocharger, especially the exhaust-gas turbocharger, and the three-way catalytic converter, may be disadvantageous from the aspect of space utilization. Another, preferably fixated and/or protected installation position of the sensor element, in particular the lambda probe, is desirable. Other installation positions for sensors, especially sensors in the broadest sense, are known from the related art.
Published German patent application document DE 10 2006 058 539 A1 describes a self-ignition engine having a pressure-based combustion control. For example, this laid-open publication describes that an engine may be equipped with exhaust-gas/fuel-ratio sensors, e.g., in an exhaust-gas manifold.
Published German patent document DE 601 02 337 T2, for example, describes a system for aiding in the regeneration of a particle filter in a self-igniting internal combustion engine. In FIG. 1 of this translation of a European patent publication, a lambda probe is disclosed, which is schematically situated between a Diesel engine and a turbocharger, which is followed by an oxidation catalytic converter.
Published German patent document DE 601 30 851 T2 describes a turbocharger control unit. It is stated that the turbocharger system has one or more sensors.
Published German patent application document 10 2008 034 680 A1 describes a cooled turbocharger housing having one or more electronic devices. In one specific development according to the present invention, it is indicated that the electronic device is a sensor device, for instance.
An orientation of a shield tube with respect to the sensor element, especially to a gas entry hole of the sensor element, is generally variable in the related art, for construction-related reasons. A preferably fixed orientation of sensor element/shield tube is desirable. Reaching the operational readiness of the sensor element, especially the lambda probe, more rapidly following an engine start would be desirable. To do so, the admission of water to the sensor element, especially the lambda probe, after the engine start preferably should be reduced. At the same time, for example, a high dynamic response of the sensor element, especially a high dynamic response of the lambda probe, to a change in the oxygen partial pressure should be ensured. In addition, it would be desirable to ensure a uniform and/or protected installation position and/or installed state of the sensor element, especially the lambda probe, in various space concepts.